I'm discovering the iOS dev environment and I realized I shouldn't have used internal TestFlight. It requires giving beta testers a role in the project, which grants them some access to App Store Connect. My bad, I assumed it worked like Android.
Tomorrow I'll set it up properly with external testing, but I'm wondering: is it possible to validate testers one by one to avoid people who didn't get an invitation from joining? iOS devs, please help an Android dev :) Shares appreciated!
@apps you can just set up the group of external Testers in AppStore Connect. They don't need a role and that way it stays invitation only if you do not change the setting explicitly. Hope that helps :)
@klyx
Thank you! That's very helpful. I don't have an iPhone myself, so I was struggling with the mobile website. I'll set it up from my computer tomorrow.
@apps you are very welcome. it is pretty straight forward on Desktop/Browser. I do most of the stuff there. just ask if you need any more guidance :)
@klyx
Much appreciated, thank you!

@apps you have to invite them by email address.

don't use a public invite link — i'm not sure if they get enumerated somehow or if someone posted the one for Feditext, but ours leaked forever ago (we made it officially public after that).

Invite external testers - Test a beta version - App Store Connect - Help - Apple Developer

Learn how to invite external testers to TestFlight in App Store Connect.

@vyr
Second reply and super useful as well, thank you for sharing this!